/*
 * Licensed to the Apache Software Foundation (ASF) under one
 * or more contributor license agreements. See the NOTICE file
 * distributed with this work for additional information
 * regarding copyright ownership. The ASF licenses this file
 * to you under the Apache License, Version 2.0 (the
 * "License"); you may not use this file except in compliance
 * with the License. You may obtain a copy of the License at
 *
 *   http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing,
 * software distributed under the License is distributed on an
 * "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
 * KIND, either express or implied. See the License for the
 * specific language governing permissions and limitations
 * under the License.
 */
#ifndef PEBBLE_RPC_PROCESSOR_DISPATCHPROCESSOR_H
#define PEBBLE_RPC_PROCESSOR_DISPATCHPROCESSOR_H

#include "source/rpc/processor/processor.h"

namespace pebble { namespace rpc { namespace processor {

/**
 * TDispatchProcessor is a helper class to parse the message header then call
 * another function to dispatch based on the function name.
 *
 * Subclasses must implement dispatchCall() to dispatch on the function name.
 */
template <class Protocol_>
class TDispatchProcessorT : public TProcessor {
public:
    virtual bool process(cxx::shared_ptr<protocol::TProtocol> in,
                            cxx::shared_ptr<protocol::TProtocol> out,
                            void* connectionContext) {
        protocol::TProtocol* inRaw = in.get();
        protocol::TProtocol* outRaw = out.get();

        // Try to dynamic cast to the template protocol type
        Protocol_* specificIn = dynamic_cast<Protocol_*>(inRaw); // NOLINT
        Protocol_* specificOut = dynamic_cast<Protocol_*>(outRaw); // NOLINT
        if (specificIn && specificOut) {
            return processFast(specificIn, specificOut, connectionContext);
        }

        // Log the fact that we have to use the slow path
        // T_GENERIC_PROTOCOL(this, inRaw, specificIn);
        // T_GENERIC_PROTOCOL(this, outRaw, specificOut);

        std::string fname;
        protocol::TMessageType mtype;
        int64_t seqid;
        inRaw->readMessageBegin(fname, mtype, seqid);

        // If this doesn't look like a valid call, log an error and return false so
        // that the server will close the connection.
        //
        // (The old generated processor code used to try to skip a T_STRUCT and
        // continue.  However, that seems unsafe.)
        if (mtype != protocol::T_CALL && mtype != protocol::T_ONEWAY) {
            GlobalOutput.printf("received invalid message type %d from client", mtype);
            return false;
        }

        return this->dispatchCall(inRaw, outRaw, fname, seqid, connectionContext);
    }

protected:
    bool processFast(Protocol_* in, Protocol_* out, void* connectionContext) {
        std::string fname;
        protocol::TMessageType mtype;
        int64_t seqid;
        in->readMessageBegin(fname, mtype, seqid);

        if (mtype != protocol::T_CALL && mtype != protocol::T_ONEWAY) {
            GlobalOutput.printf("received invalid message type %d from client", mtype);
            return false;
        }

        return this->dispatchCallTemplated(in, out, fname, seqid, connectionContext);
    }

    /**
     * dispatchCall() methods must be implemented by subclasses
     */
    virtual bool dispatchCall(pebble::rpc::protocol::TProtocol* in,
                                pebble::rpc::protocol::TProtocol* out,
                                const std::string& fname, int64_t seqid,
                                void* callContext) = 0;

    virtual bool dispatchCallTemplated(Protocol_* in, Protocol_* out,
                                    const std::string& fname, int64_t seqid,
                                    void* callContext) = 0;
};

/**
 * Non-templatized version of TDispatchProcessor, that doesn't bother trying to
 * perform a dynamic_cast.
 */
class TDispatchProcessor : public TProcessor {
public:
    virtual bool process(cxx::shared_ptr<protocol::TProtocol> in,
                        cxx::shared_ptr<protocol::TProtocol> out,
                        void* connectionContext) {
        std::string fname;
        protocol::TMessageType mtype;
        int64_t seqid;
        in->readMessageBegin(fname, mtype, seqid);

        if (mtype != protocol::T_CALL && mtype != protocol::T_ONEWAY) {
            GlobalOutput.printf("received invalid message type %d from client", mtype);
            return false;
        }

        return dispatchCall(in.get(), out.get(), fname, seqid, connectionContext);
    }

protected:
    virtual bool dispatchCall(protocol::TProtocol* in,
                            protocol::TProtocol* out,
                            const std::string& fname, int64_t seqid,
                            void* callContext) = 0;
};

// Specialize TDispatchProcessorT for TProtocol and TDummyProtocol just to use
// the generic TDispatchProcessor.
template <>
class TDispatchProcessorT<protocol::TDummyProtocol> :
    public TDispatchProcessor {}; // NOLINT
template <>
class TDispatchProcessorT<protocol::TProtocol> :
    public TDispatchProcessor {}; // NOLINT

} // namespace processor
} // namespace rpc
} // namespace pebble


#endif // PEBBLE_RPC_PROCESSOR_DISPATCHPROCESSOR_H
